Array antenna receiver device

ABSTRACT

Calibration signals are distributed to the respective output signals of a plurality of antenna elements, thereby multiplexing the distributed calibration signals with the respective signals of the plurality of antenna elements. The calibration signals are extracted from the respective output signals of the multiplexing means and modulated, and the SIR (Signal to Interference Ratio) values of the calibration signals are calculated. The SIR value as calculated by SIR calculating means each calibration period is compared with a SIR threshold value. Only when the SIR value exceeds the SIR threshold value, a demodulated result of the calibration signal is outputted. Further, in each reception branch, the calibration amount of amplitude/phase information is determined based on a reference demodulation result of the branch corresponding to the demodulation result of the branch corresponding to the demodulation result, and a user signal is corrected based on the calibration amount.

The present application is based on Japanese patent application no.2002-180070, the entire contents of which are incorporated herein byrefernce.

TECHNICAL FIELD

The present invention relates to an array antenna receiver device, andparticularly to an array antenna receiver device provided with acalibration device for correcting variations of phase (delay) andamplitude information in a plurality of reception branches.

BACKGROUND TECHNOLOGY

In a cellular mobile communication system and the like, such a systemwherein an array antenna receiver device composed of a plurality ofantenna elements having high correlations one another is used, whereby areception directivity pattern is formed such that a reception gainincreases with respect to an arrival direction of a desired signal,while a reception gain decreases with respect to interferences due to aninterference or a delay wave from other users is heretofore studied withan intention of high speed/high quality of signals and increase in acapacity of subscribers.

Incidentally, in an array antenna receiving device having a plurality ofradio receiving parts of antennas, generally, amplitude and phasevariations in the radio receiving parts of the antennas connected toantenna elements, respectively, are independently varied every second.Accordingly, it is necessary for compensating such variations of phaseand amplitude at the time of forming a reception directivity pattern,and such operation is called by the name of calibration.

As a conventional calibration method, there is, for example, a mannerdescribed in Japanese Patent Application Laid-open No. 11-46180(Calibration apparatus for array antenna receiver device) wherein aknown calibration signal is input to each radio receiving part connectedto each antenna element, a demodulated result of the calibration signalis used to compensate phase (delay) and amplitude variations in eachradio receiving part which varies independently every second.

FIG. 1 is a block diagram illustrating an array antenna receiver devicefor exemplifying a calibration described in the above patent applicationlaid-open official gazette. The array antenna receiver device iscomposed of an array antenna 901, multiplexing circuits 903 ₁ to 903_(N), a radio receiving part 904 ₁ of an antenna 1 to a radio receivingpart 904 _(N) of an antenna N corresponding to antenna elements,respectively, a signal processing part 905 ₁ of a user 1 to a signalprocessing part 905 _(M) of a user M corresponding to the number ofusers, a calibration signal generating part 906, a calibration radiotransmitting part 907, a power level variable part 908, N distributors909, and a calibration signal processing part 910 wherein N of the Ndistributors corresponds to the number of antenna elements (multiplexingcircuits).

The array antenna 901 is composed of the N antenna elements 902 ₁ to 902_(N). The N antenna elements 902 ₁ to 902 _(N) are closely disposed soas to have correlations among reception signals of the respectiveantenna elements, wherein desired signals are multiplexed with aplurality of interference signals are received. For the sake ofdiscriminating a usual diversity construction, N of the number ofantenna elements is to be three or more.

To the multiplexing circuits 903 ₁ to 903 _(N), N outputs of the Ndistributors 909 and outputs of the antenna elements 902 ₁ to 902 _(N)are input to perform multiplexing in a radio transmission band, and theresults are output to the radio receiving part 904 ₁ of the antenna 1 tothe radio receiving part 904 _(N) of the antenna N. A multiplexingmethod is not limited, but there is, for example, code multiplexing.

Each of the radio receiving part 904 ₁ of the antenna 1 to the radioreceiving part 904 _(N) of the antenna N is composed of devices such asa low noise amplifier, a band pass filter, a mixer, synthesizers, an AGC(Auto Gain Controller), a demodulator, a low pass filter, and ananalog-to-digital converter (ADC) An explanation will be made hereinupon the radio receiving part 904 _(N) of the antenna N as an example.To the radio receiving part 904 _(N) of the antenna N, an output of themultiplexing circuit 903 _(N) is input to perform amplification of aninput signal, a frequency conversion from a radio transmission band to abase band, demodulation, an analog-to-digital conversion and the like,and the results are output to the signal processing part 905 ₁ of theuser 1 to the signal processing part 905 _(M) of the user M and thecalibration signal processing part 910.

To the calibration signal processing part 910, outputs of the radioreceiving part 904 ₁ of the antenna 1 to the radio receiving part 904_(N) of the antenna N are input to extract calibration signals in inputsignals thereby to detect phase/amplitude information of the antenna 1to phase/amplitude information of the antenna N, and the results areoutput to the signal processing part 905 ₁ of the user 1 to the signalprocessing part 905 _(M) of the user M. It is to be noted that acalibration signal multiplexed with an input signal is extractable.

To the signal processing part 905 ₁ of a user 1 to a signal processingpart 905 _(M) of a user M, outputs of the radio receiving part 904 ₁ ofthe antenna 1 to the radio receiving part 904 _(N) of the antenna N andthe phase/amplitude information of the antenna 1 to the phase/amplitudeinformation of the antenna N being outputs from the calibration signalprocessing part 910 are input. Then, a reception directivity pattern isformed in such that a reception gain increases with respect to a usersignal arrival direction in each user, while a reception gain decreaseswith respect to interferences from other users or an interference due toa delay wave while compensating outputs from the radio receiving part904 ₁ of the antenna 1 to the radio receiving part 904 _(N) of theantenna N by the use of the phase/amplitude information of the antenna 1to the phase/amplitude information of the antenna N, and a demodulationsignal of the user 1 to a demodulating signal of the user M received bythe reception directivity pattern are output.

The calibration signal generating part 906 produces a calibration signalin a base band, and the resulting calibration signal is output to thecalibration radio transmitting part 907. To the calibration radiotransmitting part 907, a calibration signal in a base band being anoutput of the calibration signal generator 906 is input to perform adigital-to-analog conversion, a frequency conversion from a base band toa radio transmission band and the like, and the results are output tothe power level variable part 908.

To the power level variable part 908, a calibration signal in the samefrequency band as that of a reception signal derived from the antennaelements 902 ₁ to 902 _(N) being an output of the calibration radiotransmitting part 907 is input, and the results are output to the Ndistributors 909 at an arbitrary electric power level. The Ndistributors N-distribute calibration signals in a radio transmissionband being outputs of the power level variable part, and the results areoutput to the N multiplexing circuits 903 ₁ to 903 _(N), respectively.

Each of signals received by the N antenna elements 902 ₁ to 902 _(N)contains a desired (user) signal component, an interference signalcomponent, and thermal noises. Moreover, a multipath component exists,respectively, in the desired signal component and the interferencesignal component, and these signal components arrived usually fromdifferent directions.

The array antenna receiver device of FIG. 1 discriminates respectivesignal components of different arrival directions with the use ofphase/amplitude information of the respective signals received by the Nantenna elements 902 ₁ to 902 _(N) to form a reception directivitypattern.

In these circumstances, there is a case when phase/amplitude variationsappear inside the respective radio receiving parts dependent upon aconstructional device of the radio receiving part 904 ₁ of the antenna 1to the radio receiving part 904 _(N) of the antenna N. As a result,different information from primary phase/amplitude information of therespective signals received by the antenna elements 902 ₁ to 902 _(N) isgiven to the signal processing part 905 ₁ of the user 1 to the signalprocessing part 905 _(M) of the user M, so that it becomes impossible todiscriminate correctly the respective signal components, and thus, anideal reception directivity pattern cannot be formed.

Accordingly, a reception signal is multiplexed with a calibration signalin the same frequency band as that of the reception signal received bythe antenna elements 902 ₁ to 902 _(N) to detect phase/amplitudeinformation of a calibration signal extracted from the respectiveoutputs of the radio receiving part 904 ₁ of the antenna 1 to the radioreceiving part 904 _(N) of the antenna N in the calibration signalprocessing part 910, whereby phase/amplitude information given by thesignal processing part 905 ₁ of the user 1 to the signal processing part905 _(M) of the user M is corrected.

When multiplexed with a calibration signal as described above, acalibration becomes possible even in case of working the array antennareceiver device. Namely, a calibration signal is in a state where it ismultiplexed with a reception signal from a mobile phone, so that only acalibration signal component can be extracted. An example of such caseas described above includes code multiplexing.

Non-linear circuits (particularly, an AGC) contained in the radioreceiving part 904 ₁ of the antenna 1 to the radio receiving part 904_(N) of the antenna N exhibit different manners of phase/amplitudevariations dependent on a reception electric power level. Accordingly, acalibration signal of each output of the radio receiving part 904 ₁ ofthe antenna 1 to the radio receiving part 904 _(N) of the antenna N isextracted while changing a calibration signal power level with the powerlevel variable circuit 908 to detect phase/amplitude information,whereby a calibration amount to be applied to phase/amplitudeinformation given to the signal processing part 905 ₁ of the user 1 tothe signal processing part 905 _(M) of the user M in each calibrationsignal power level is determined.

The array antenna receiver device having such calibration means asdescribed above can correct the phase/amplitude information given to thesignal processing part 905 ₁ of the user 1 to the signal processing part905 _(M) of the user M, even in a case where phase/amplitude variationsappear inside the radio receiving part 904 ₁ of the antenna 1 to theradio receiving part 904 _(N) of the antenna N at the time ofapplication thereof. Furthermore, it is possible to achieve a highprecision in response to a power level of a reception signal. Thus,according to the array antenna receiver device of FIG. 1, respectivesignal components having different arrival directions one another arediscriminated with the use of phase/amplitude information of respectivesignals received by the N antenna elements 902 ₁ to 902 _(N), so that anideal reception directivity pattern can be formed.

However, the above-mentioned conventional array antenna receiver deviceinvolves the following problems. Namely, a first problem is in that theoptimum calibration cannot be applied to all the reception branches inthe case when a calibration is conducted at the time of application ofthe system. The reason of which is in that a magnitude of a receptionsignal input from each antenna element (a communication signal from amobile phone, noises, an interference signal from other systems) exhibita remarkable dispersion as a result of being affected adversely byfading and the like, so that a ratio of a calibration signal input toeach reception branch in a constant equal electric power and a receptionsignal being an interference signal from an antenna element differsremarkably with each other.

Moreover, a second problem is in that a calibration of a high precisioncannot be achieved in the case when a trouble occurs in a certainreception branch. The reason of which is in that the conventional arrayantenna receiver device is not provided with a means for judging signalquality of a calibration signal and a means for excluding the receptionbranch in which a trouble occurs.

A third problem is in that reception sensitivity of the array antennareceiver device deteriorates as a result of implementing a calibrationin case of working the system. The reason of which is in that acalibration signal is a mere interference signal for a communicationsignal (desired wave) with a mobile phone and which is input from anarray antenna, besides, particularly, when a calibration signal of ahigh level is input, an interference signal component increases.

A fourth problem is in that when a calibration is conducted at the timeof working the system, the number of users in the system decreases. Thereason of which is in that a calibration signal in question becomes aninterference wave to deteriorate a ratio of a user signal from a mobilephone with respect to such interference signal, so that a transmissionelectric power in the mobile phone increases for demodulating the usersignal with desired signal quality in its radio base stationinstallation.

DISCLOSURE OF INVENTION

An object of the present invention is to provide an array antennareceiver device and a calibration method of array antenna receptionsignals by which the optimum calibration can be made upon all thereception branches, a calibration with a high precision can be conductedeven if a trouble occurs in any reception branch, besides there isscarce deterioration in reception sensitivity, and the number of usersin a cellular system is not decreased substantially.

In order to achieve the above-described object, the present inventionprovides an array antenna receiver device comprising a plurality ofantenna elements; a means for outputting calibration signals; a meansfor distributing the calibration signals to the plurality of the antennaelements; a plurality of multiplexing means each of which multiplexeseach calibration signal distributed with a signal input from each of theplurality of the antenna elements; a plurality of SIR calculating meanseach of which extracts and demodulates each calibration signal from anoutput signal of the multiplexing means to calculate a SIR (Signal toInterference Ratio) value, and further compares the SIR value calculatedwith a previously established SIR threshold value thereby to outputreception branch information and a demodulation result of thecalibration signal in only the case when the SIR value calculatedexceeds the SIR threshold value; a means for storing a referencedemodulation result which is previously established in each receptionbranch; a means for detecting a calibration amount of amplitude/phaseinformation in each reception branch based on the demodulation resultand the reference demodulation result in a branch corresponding to thestoring means; and means for correcting a user signal based on thecalibration amount.

Furthermore, in order to achieve the above-described object, the presentinvention provides an array antenna receiver device comprising aplurality of antenna elements; a means for outputting calibrationsignals; a plurality of multiplexing means for multiplexing each outputsignal from the plurality of the antenna elements with each calibrationsignal; a means for changing over connections of the output means withthe plurality of the multiplexing means to supply calibration signals ina time sharing manner to the plurality of the multiplexing means; aplurality of SIR calculating means for extracting and demodulatingsuccessively calibration signals from output signals of one multiplexingmeans selected respectively in synchronous with supplying operations ofthe calibration signals from the supplying means in accordance with thetime sharing manner to calculate a SIR (Signal to Interference Ratio)value, and further compares the SIR value calculated with a previouslyestablished SIR threshold value thereby to output reception branchinformation and a demodulation result of each calibration signal in onlythe case when the SIR value calculated exceeds the SIR threshold value;a means for storing a reference demodulation result which is previouslyestablished in each reception branch; a means for detecting acalibration amount of amplitude/phase information in each receptionbranch based on the demodulation result and the reference demodulationresult in a branch corresponding to the storing means; and means forcorrecting a user signal based on the calibration amount.

Moreover, in order to achieve the above-described object, the presentinvention provides a calibration method of antenna reception signalscomprising the steps of multiplexing a reception signal input in everyplural antenna elements with a calibration signal distributed in theevery plural antenna elements; extracting and demodulating a calibrationsignal from the multiplexed signal to calculate a SIR (Signal toInterference Ratio) value of the calibration signal; comparing the SIRvalue calculated with a previously established SIR threshold value tooutput reception branch information and a demodulation result of thecalibration signal in only the case when the calculated SIR valueexceeds the SIR threshold value; detecting a calibration amount ofamplitude/phase information in every reception branches based on thedemodulation result and the previously established referencedemodulation result; and correcting a user signal based on thecalibration amount.

Furthermore, in order to achieve the above-described object, the presentinvention provides a calibration method of antenna reception signalscomprising the steps of multiplexing a reception signal input in everyplural antenna elements with each calibration signal supplied in a timesharing manner in the every plural antenna elements; extracting anddemodulating successively calibration signals from one multiplexingsignal selected respectively in synchronous with supplying operations ofthe calibration signals in accordance with the time sharing manner tocalculate a SIR (Signal to Interference Ratio) value of each calibrationsignal; comparing the SIR value calculated with a previously establishedSIR threshold value to output reception branch information and ademodulation result of the calibration signal in only the case when thecalculated SIR value exceeds the SIR threshold value; detecting acalibration amount of amplitude/phase information in every receptionbranches based on the demodulation result and the previously establishedreference demodulation result; and correcting a user signal based on thecalibration amount.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating an array antenna receiver deviceof a conventional example;

FIG. 2 is a block diagram illustrating a construction of a firstembodiment according to an array antenna receiver device of the presentinvention;

FIGS. 3( a), (b), (c), (d), (e), and (f) are representations eachshowing an electric power distribution of a calibration signal and auser signal in each reception branch of the embodiment in FIG. 2;

FIG. 4 is a representation showing an example of asynchronouscalibration periods in respective reception branches of the embodimentin FIG. 2;

FIG. 5 is a diagram for explaining a relationship between a referencedemodulation result and a demodulation result of a calibration signal inthe first embodiment;

FIG. 6 is a block diagram illustrating a second embodiment of thepresent invention;

FIG. 7 is a diagram for explaining an example of calibration periods incase of changing over 1: N switches of the second embodiment;

FIG. 8 is a block diagram illustrating a third embodiment of the presentinvention; and

FIG. 9 is a block diagram illustrating a fourth embodiment.

BEST MODE FOR EMBODYING THE INVENTION

In the following, embodiments according to the present invention will bedescribed in detail by referring to the accompanying drawings.

First Embodiment

FIG. 2 is a block diagram illustrating a construction of the firstembodiment of an array antenna receiver device according to the presentinvention. In FIG. 2, an array antenna 101 is composed of N antennaelements 102 ₁ to 102 _(N), and these antenna elements are disposedclosely with each other so as to increase correlativities in respectiveantennas.

Multiplexing circuits 103 ₁ to 103 _(N) are connected with the antennaelements 102 ₁ to 102 _(N), respectively. To the multiplexing circuits103 ₁ to 103 _(N) calibration signals output from a calibration radiotransmitting part 107 and N-distributed by N-distributors, and outputsof the respective antenna elements 102 ₁ to 102 _(N) are input, they aremultiplexed in a radio transmission band, and the multiplexed resultsare output to a radio receiving part 104 ₁ of an antenna 1 to a radioreceiving part 104 _(N) of an antenna N connected to the multiplexingcircuits 103 ₁ to 103 _(N), respectively.

Each of the radio receiving part 104 ₁ of the antenna 1 to the radioreceiving part 104 _(N) of the antenna N is composed of a low noiseamplifier, a band pass filter, a mixer, synthesizers, a total receivedpower detecting part, an AGC (Auto Gain Controller), a demodulator, alow pass filter, an analog-to-digital converter and the like. Outputsfrom the radio receiving part 104 ₁ of the antenna 1 to the radioreceiving part 104 _(N) of the antenna N are connected to a signalprocessing part 105 ₁ of a user 1 to a signal processing part 105 _(M)of a user M and a SIR (Signal to Interference Ratio) calculating part111 ₁ to a SIR calculating part 111 _(N), respectively. The SIRcalculating part 111 ₁ to the SIR calculating part 111 _(N) are providedso as to correspond to a radio receiving part 104 ₁ of the antenna 1 toa radio receiving part 104 _(N) of the antenna N, respectively.

Outputs of the SIR calculating part 111 ₁ to the SIR calculating part111 _(N) for extracting calibration signals and calculating STRs areconnected to a calibration signal processing part 110, while outputsfrom a SIR threshold value establishing part 112 for establishingarbitrarily SIR threshold values required for calibrations are connectedto the SIR calculating part 111 ₁ to the SIR calculating part 111 _(N)When a calibration signal is provided in the form of a code multiplexedsignal, reverse diffusion is conducted for extracting a calibrationsignal.

A reference calibration result storing part 113 is connected with thecalibration signal processing part 110 to output reference demodulationresults (reference demodulation symbol points) in every receptionbranches.

To the calibration signal processing part 110, reception branchinformation (a signal indicating that it is received by which branch)being outputs of the SIR calculating part 111 ₁ to the SIR calculatingpart 111 _(N), and demodulation results (demodulation symbol points) aswell as reference demodulation results being outputs of the referencecalibration result storing part 113 are input. Then, the calibrationprocessing part 110 compares these modulation results with the referencemodulation results to detect amplitude/phase information of the antenna1 to amplitude/phase information of the antenna N (indicating finitedifferences between the demodulation results and the referencedemodulation results=calibration information), and the resultingcalibration information is output to the signal processing part 105 ₁ ofthe user 1 to the signal processing part 105 _(M) of the user M,respectively.

A calibration signal generating part 106 produces calibration signals ina base band, and the calibration signals produced are output to acalibration radio transmitting part 107. The calibration signalgenerating part 106 may produce an arbitrary symbol pattern as acalibration signal.

To the calibration radio transmitting part 107, calibration signals inthe base band being outputs of the calibration signal generating part106 are input to perform a digital-to-analog conversion, a frequencyconversion from base band to radio transmission band and the like, andthe results are output to N distributors. Outputs of the N distributors109 which distribute calibration signals input from the calibrationradio transmitting part 107 into the number N of reception branches areconnected to the multiplexing circuits 103 ₁ to 103 _(N), respectively.

In the following, operations in the first embodiment will be described.First, the array antenna 101 is composed of the N antenna elements 102 ₁to 102 _(N), and these N antenna elements are closely disposed from oneanother so as reception signals in the respective antenna elements tohave high correlations with each other. Each of the antenna elementsreceives a signal communicating with a mobile phone (hereinafterreferred to as “user signal”) and another signal which is multiplexed bya plurality of interference signals. When the number of antenna elementsincreases in reality, correlations among antenna elements which are notadjacent to each other and positioned apart from one another come to below, so that an electric power of the multiplexed signal receivedexhibits a remarkable dispersion. In other words, a different electricpower is input to each antenna element of an array antenna receiverdevice.

The multiplexing circuits 103 ₁ to 103 _(N) are connected to the antennaelements 102 ₁ to 102 _(N), and calibration signals distributed to Noutputs by the N distributors and outputs of the respective antennaelements 102 ₁ to 102 _(N) are input to the multiplexing circuits 103 ₁to 103 _(N), whereby multiplexing is conducted in a radio transmissionband, and the results are output to the radio receiving part 104 ₁ ofthe antenna 1 to a radio receiving part 104 _(N) of the antenna Nconnected respectively to the multiplexing circuits 103 ₁ to 103 _(N).

In this case, a calibration signal in a base band produced in thecalibration signal generating part 106 is amplified andfrequency-converted by the calibration radio transmitting part 107 totransmit the resulting signal as a known signal. When it is intended tosuppress deterioration in receiver sensitivity of a user signal to 0.2dB or less with the use of a calibration signal, it is equal to that anoise power level does not deteriorate up to 0.2 dB at the most, so thatan electric power ratio x with respect to a calibration signal levelcomes to be x<−13.267 dB from 0.2>10×log(10^(0/10)+10^(x/10)), when thenoise power level is considered to be 0 dB. Accordingly, it is requiredthat an electric power for transmitting a calibration signal is to be afixed level lower than a noise electric power level by −13.267 dB orless in order that receiver sensitivity of an array antenna receiverdevice is scarcely affected adversely.

In this case, those output from the multiplexing circuits 103 ₁ to 103_(N) are calibration signals, user signals, interference signals fromthe other systems, and thermal noises. In this connection, when it isconsidered that a sum of these signals is a total reception electricpower, since the calibration signals and the thermal noises are constantelectric powers, a difference of the total reception electric poweroutput from the respective multiplexing circuits to the radio receivingpart 104 ₁ of the antenna 1 to the radio receiving part 104 _(N) of theantenna N comes to be a difference of “the user signals and theinterference signals of the other systems” input from the respectiveantenna elements as they are.

Although The radio receiving part 104 ₁ of the antenna 1 to the radioreceiving part 104 _(N) of the antenna N perform amplification,frequency conversion, and analog-to-digital conversion, they arecontrolled by the AGCs contained in the radio receiving parts of theantennas such that the output levels are always maintained at constantlevels. Therefore, an electric power ratio of calibration signals inoutputs of the radio receiving parts of the antennas becomes high in thecase where user signals and interference signals from other systems arelow, while The ratio becomes low in the case where the user signals andinterference signals from other systems are high.

For the sake of simplicity in explanation, electric power distributionsin N reception branches are shown (prior to applying gain control by anAGC) with only aiming at each calibration signal and each communicationsignal (user signal) FIGS. 3( a) to (c) show states where onlycalibration signals are input to the N reception branches, while FIGS.3( d) to (f) show states where calibration signals of the same levelsand communication signals of different electric powers are input to theN reception branches.

Since an output from a radio receiving part of an antenna is controlledby an AGC so as to be a constant electric power, a calibration signaland a user signal are output from each radio receiving part of anantenna with the same electric power in each reception branch whilemaintaining a ratio of a calibration signal and a user signal as it isas shown in FIGS. 3( d) to (f) Accordingly, when a calibration signal isextracted and demodulated, and further a SIR of the calibration signalis calculated in each SIR calculating part, the results are a SIR ofbranch 1>a SIR of branch 2>a SIR of branch N.

In order to increase a SIR of a calibration signal in a calibration, itis general to prolong a period of time for averaging results obtained,but a required length of an averaging time for ensuring a SIR requiredfor calibration comes to be branch 1<branch 2<branch N. In other words,reception branch information and a demodulation result are output withthe shortest calibration period in the reception branch 1 among the SIRcalculating part 111 ₁ to the SIR calculating part 111 _(N), then, thereception branch 2 follows thereto, and the reception branch N has thelatest order, so that calibration periods differ from one another.

FIG. 4 shows a state where the respective reception branches havedifferent calibration periods. The term “calibration period” means aperiod of time for extending from outputting reception branchinformation and demodulation results to outputting newly receptionbranch information and demodulation results in the respective SIRcalculating parts.

The SIR threshold establishing part 112 can establish arbitrarily a SIRthreshold value of a calibration signal, and SIR threshold valuesestablished are output to the SIR calculating part 111 ₁ to the SIRcalculating part 111 _(N). The SIR calculating part 111 ₁ to the SIRcalculating part 111 _(N) extract and demodulate calibration signalsfrom all the reception signals output from the radio receiving part 104₁ of the antenna 1 to the radio receiving part 104 _(N) of the antennaN, and calculate SIRs of the calibration signals, respectively.

In the respective SIR calculating parts, the SIR values of thecalibration signals calculated and SIR threshold values from the SIRthreshold value establishing part 112 are compared, and reception branchinformation and demodulation results of the calibration signals areoutput to the calibration signal processing part 110 from only the SIRcalculating parts relating to which a SIR value of a calibration signalcalculated exceeds a SIR threshold value. In this case, calibrationperiods differ from one another in every reception branches or in eachperiod of time in even the same branch as mentioned above. Thus, in eachSIR calculating part, a SIR of a calibration signal is calculated, a SIRvalue and a SIR threshold value are compared until the SIR valuecalculated exceeds the SIR threshold value, and reception branchinformation and a demodulation result of a calibration signal are outputto the calibration signal processing part 110 at the time when the SIRvalue exceeds the SIR threshold value.

In the case where a SIR of a calibration signal calculated in each SIRcalculating part does not exceed a SIR threshold value from the SIRthreshold value establishing part 112 after elapsing an averaging periodof time for obtaining a sufficient SIR (for example, one minute), evenif user signals or interference signals from other systems of high powerare further input from the respective antenna elements, receptioninformation and a trouble detection signal are output from acorresponding SIR calculating part to the calibration signal processingpart 110.

It may be considered that modulation results output from the SIRcalculating part 111 ₁ to the SIR calculating part 111 _(N) as a resultof exceeding SIR threshold values assure a precision necessary forcalibration. Hence, demodulation results input from the respective SIRcalculating parts are compared with reference demodulation results fromthe reference calibration result storing part 113 in every receptionbranches, i.e. reference demodulation results of corresponding receptionbranches in the calibration signal processing part 110 to extract avariation amount of amplitude/phase in each branch, thereby to update acalibration amount, and the results are output to the signal processingpart 105 ₁ of the user 1 to the signal processing part 105 _(M) of theuser M, respectively.

In this connection, reference modulation results being outputs of thereference calibration result storing part 113 mean reference symbolpoints of respective reception branches wherein amplitude/phaseproperties are aligned at N reception branches, and calibration amountsare calculated from variation amounts of the demodulation results(symbol points) output from the respective SIR calculating partscorresponding to the respective reference symbol points. A relationshipbetween a reference symbol point (I_(ref), Q_(ref)) in a certainreception branch and a demodulation result (I_(n), Q_(n)) output from aSIR calculating part connected to the branch is shown in FIG. 5.

On one hand, the calibration signal processing part 110 controls thesignal processing part 105 ₁ of the user 1 to the signal processing part105 _(M) of the user M in such that a user signal from a certain branchis made ineffective because a trouble appears in the questioned branchin the case when reception branch information and a trouble detectionsignal are input from the SIR calculating part.

To the signal processing part 105 ₁ of the user 1 to the signalprocessing part 105 _(M) of the user M, outputs from the radio receivingpart 104 ₁ of the antenna 1 to the radio receiving part 104 _(N) of theantenna N and amplitude/phase information of the antenna 1 toamplitude/phase information of the antenna N output successively fromthe calibration signal processing part 110 are input, whereby areception directivity pattern is formed in such that a reception gainincreases with respect to a user signal arrival direction, whilst areception gain decreases with respect to interferences from other usersand interferences due to delay waves in every users while correctingoutputs of the radio receiving part 104 ₁ of the antenna 1 to the radioreceiving part 104 _(N) of the antenna N by the use of theamplitude/phase information of the antenna 1 to the amplitude/phaseinformation of the antenna N, and thus, a demodulation signal of a user1 to a demodulation signal of a user M which are received by thereception directivity pattern are output.

As described above, when a calibration signal of a fixed electric powerwhich deteriorates scarcely a user signal is used, an averaging processis continued until a SIR of a calibration signal extracted from therespective radio reception parts exceeds a SIR threshold value, and amodulation result (I_(n), Q_(n)) of a calibration signal is output inonly the case when the SIR of a calibration signal extracted from therespective radio reception parts reaches the SIR threshold value. Thenthe result obtained is compared with a demodulation result (I_(ref),Q_(ref)) being a reference, whereby a calibration having the mostefficient calibration period with respect to respective receptionbranches and maintaining at a certain calibration accuracy can be made.Furthermore, it becomes also possible to exclude a reception branch inwhich a trouble appears.

Second Embodiment

FIG. 6 is a block diagram illustrating an array antenna receiver of thesecond embodiment according to the present invention wherein parts shownin FIG. 6 corresponding to those of FIG. 2 are designated by the samereference characters as those of FIG. 2, respectively, and a detaileddescription therefor is omitted. A difference of the second embodimentfrom that of the first embodiment of FIG. 2 resides in such a point thata 1: N switches change-over part 114 is used in place of the Ndistributors 109, and calibration signals are supplied to multiplexingcircuits 103 ₁ to 103 _(N) in accordance with a time sharing manner, andthe other construction is the same as that of FIG. 2.

The multiplexing circuits 103 ₁ to 103 _(N) are connected to antennaelements 102 ₁ to 102 _(N) and N outputs of the 1: N switcheschange-over part 114. To the multiplexing circuits 103 ₁ to 103 _(N),outputs of the antenna elements 102 ₁ to 102 _(N) and a calibrationsignal output from a calibration radio transmitting part 107 to besupplied to only one arbitrary multiplexing circuit by the 1: N switcheschange-over part 114 are input, whereby multiplexing is made in a radiotransmitting band, and results are output to a radio receiving part 104₁ of an antenna 1 to a radio receiving part 104 _(N) of an antenna Nconnected respectively to the multiplexing circuits 103 ₁ to 103 _(N).

Outputs of a SIR calculating part 111 ₁ to a SIR calculating part 111_(N) each of which extracts or demodulates a calibration signal andcalculates a SIR are connected to a calibration signal processing part110 and the 1: N switches change-over part 114, while outputs of a SIRthreshold value establishing part 112 wherein a SIR threshold valuerequired for calibration is arbitrarily established are connected to theSIR calculating part 111 ₁ to a SIR calculating part 111 _(N) It is tobe noted that when a calibration signal is provided in the form of acode multiplexed signal, reverse diffusion is conducted for extracting acalibration signal.

To a calibration radio transmitting part 107, a calibration signal in abase band which is an output of a calibration signal transmitting part106 is input to implement a digital-to-analog conversion, and afrequency conversion from a base band to a radio transmission band, andthe results are output to the 1: N switches change-over part 114. Noutputs of the 1: N switches change-over part 114 which outputscalibration signals input from the calibration radio transmitting part107 to only one arbitrary multiplexing circuit are connected to themultiplexing circuits 103 ₁ to 103 _(N), respectively.

In the following, operations of the second embodiment will be describedwherein the same operations as those of the first embodiment are simplydescribed.

To the 1: N switches change-over part 114, a calibration signal being anoutput of the calibration radio transmitting part 107 is input to outputthe calibration signal to only one arbitrary multiplexing circuit in theN multiplexing circuits 103 ₁ to 103 _(N) connected to the N switcheschange-over part 114. Furthermore, reception branch information anddemodulation results are input from respective SIR calculating parts tothe 1: N switches change-over part 114, and the 1: N switcheschange-over part 114 controls change-over of connections with themultiplexing circuits based on reception branch information.

For instance, it is arranged in such that the 1: N switches change-overpart 114 is changed over so as to be connected in such order of themultiplexing circuits 103 ₁, 103 ₂, . . . 103 _(N). In this case, onlythe output signals from the SIR calculating parts corresponding toreception branches connected with the 1: N switches change-over part 114are made to be effective, while output signals from the SIR calculatingparts which are not connected with the 1: N switches change-over part114 are made to be ineffective.

The multiplexing circuits 103 ₁ to 103 _(N) are connected to the antennaelements 102 ₁ to 102 _(N), respectively, to which calibration signalsinput to only one arbitrary multiplexing circuit by means of the 1: Nswitches change-over part 114 and outputs of the respective antennaelements 102 ₁ to 102 _(N) are input, whereby multiplication isconducted in a radio transmission band, and the results are output tothe radio receiving part 104 ₁ of the antenna 1 to the radio receivingpart 104 _(N) of the antenna N connected respectively to themultiplexing circuits 103 ₁ to 103 _(N). In other words, multiplicationof signals input from the antenna elements with calibration signals isimplemented in only one multiplexing circuit selected by the 1: Nswitches change-over part 114 among the multiplication circuits, so thatthose output from the other multiplexing circuits are merely receptionsignals input from antenna elements.

The SIR threshold value establishing part 112 can establish arbitrarilya SIR threshold value of a calibration signal, and outputs the SIRthreshold value established. The respective SIR calculating partsextract and demodulate calibration signals from reception signals outputfrom radio receiving parts of antennas, and calculate SIRs of thecalibration signals as in the case of the first embodiment. Furthermore,the SIRs of the calibration signals calculated are compared with SIRthreshold values from the SIR threshold establishing part 112, andreception branch information and demodulation results of calibrationsignals from only a SIR calculating part in which a calculated SIR valueexceeds a SIR threshold value are output to a calibration signalprocessing part 110 in the respective SIR calculating parts.

In this case, N multiplexing circuits are successively changed over bythe 1: N switches part 114, N SIR calculating parts calculatesuccessively SIRs of calibration signals in response thereto, andcompare the calculated SIR values with SIR threshold values. Asdescribed above, the SIRs are calculated in the SIR calculating part inevery predetermined periods according to a time sharing manner of the 1:N switches change-over part 114, and reception branch information anddemodulation results of calibration signals are output to thecalibration signal processing part 110 at the time when a calculated SIRvalue exceeds a SIR threshold value.

The calibration signal processing part 110 compares the demodulationresults with reference demodulation results of corresponding receptionbranches from a reference calibration result storing part 113 to updatea calibration amount, and it is output to each user signal processingpart. Operations of the calibration signal processing part 110 are thesame as those of FIG. 2. It is to be noted that reception branchinformation and the like from the respective SIR calculating parts areoutput to the 1: N switches change-over part 114, and connections withmultiplexing circuits are changed over based on the information in the1: N switches change-over part 114.

Moreover, when an SIR of a calibration signal calculated in each SIRcalculating part does not exceed a SIR threshold value from the SIRthreshold value establishing part 112, reception branch information anda trouble detection signal are output to the calibration signalprocessing part 110 from the corresponding SIR calculating part as inthe case of the first embodiment, even though user signals orinterference signals of a high electric power from other systems areinput from respective antenna elements and after the lapse of anaveraging period of time sufficient to obtain a SIR (e.g. one minute).

As mentioned above, when the 1: N switches which obtain a calibrationsignal of a fixed electric power which does scarcely deteriorate a usersignal and supply a calibration signal to only one arbitrarymultiplexing circuit are used to perform an averaging process until aSIR of a calibration signal extracted from each radio receiving partexceeds a SIR threshold value, and a demodulation result (I_(n), Q_(n))of the calibration signal is output in only the case when reached thethreshold value, whereby the result is compared with a demodulationresult (I_(ref), Q_(ref)) being reference, so that a calibration whichmaintains at a constant precision in time sharing manner can beconducted with respect to respective reception branches. A situation ofa calibration period wherein a control processing is performed inaccordance with the present embodiment is shown in FIG. 7.

Third Embodiment

FIG. 8 is a block diagram illustrating a construction of an arrayantenna receiver of the third embodiment according to the presentinvention wherein parts shown in FIG. 8 corresponding to those of FIG. 6are designated by the same reference characters as those of FIG. 6,respectively, and a detailed description therefor is omitted. Adifference of the third embodiment from that of the second embodimentresides in such a point that transmission electric power control is madein every reception branches by the use of a power level variable part108, and the other construction is the same as that of the secondembodiment.

Either outputs from a SIR calculating part 111 ₁ to a SIR calculatingpart 111 _(N) wherein a calibration signal is extracted and demodulated,and further, a SIR is calculated are connected to a calibration signalprocessing part 110 and a 1: N switches change-over part 114, whileoutputs of a SIR threshold value establishing part 112 wherein a SIRthreshold value required for a calibration is arbitrarily establishedare connected to the SIR calculating part 111 ₁ to the SIR calculatingpart 111 _(N). Furthermore, the other outputs of the SIR calculatingpart 111 ₁ to the SIR calculating part 111 _(N) are connected to thepower level variable part 108. Moreover, when a calibration signal isprovided in the form of a code multiplexed signal, reverse diffusion isconducted for extracting a calibration signal.

To a calibration radio transmitting part 107, a calibration signal in abase band which is an output of a calibration signal transmitting part106 is input to implement a digital-to-analog conversion, and afrequency conversion from a base band to a radio transmitting band, andthe resulting outputs are connected to the power level variable part108. The power level variable part 108 implements transmission electricpower control with respect to a calibration signal input from thecalibration radio transmitting part 107 in accordance with atransmission electric power control signal output from each SIRcalculating part, and the resulting output is connected to the 1: Nswitches change-over part 114.

In this case, a term “transmission electric power control signal” outputfrom a SIR calculating part means a signal for controlling atransmission electric power of a calibration signal in response to acalculated SIR value, and a manner of control in this signal is suchthat when a SIR value has the smaller value, a transmission electricpower of a calibration signal makes to be the larger, while when the SIRvalue exhibits the larger value, a transmission electric power of thecalibration signal makes to be the smaller.

In the following, operations of the third embodiment will be described.In the SIR threshold value establishing part 112, a SIR threshold valueof a calibration signal can be arbitrarily established, and a SIRthreshold value established is output. The SIR calculating part 111 ₁ tothe SIR calculating part 111 _(N) extract calibration signals fromreception signals output from a radio receiving part 104 ₁ of an antenna1 to a radio receiving part 104 _(N) of an antenna N, respectively, anddemodulate them to calculate SIRs of the calibration signals.

Reception branch information and demodulation results are output fromonly a SIR calculating part wherein a SIR of a calibration signalcalculated in each radio receiving part of an antenna exceeds a SIRthreshold value output from the SIR threshold value establishing part112 to the calibration signal processing part 110 and the 1: N switcheschange-over part 114. Moreover, the SIR calculating part 111 ₁ to theSIR calculating part 111 _(N) calculate a split-second SIR of acalibration signal in each reception branch, and output a transmissionelectric power control signal as mentioned above to the power levelvariable part 108 in order to conduct transmission electric powercontrol of a calibration signal.

To the power level variable part 108, a calibration signal of a fixedlevel output from the calibration radio transmitting part 107 is inputto control a transmission electric power of the calibration signal inaccordance with a transmission electric power control signal output fromeach SIR calculating part, whereby the calibration signal of theelectric power optimized in a reception branch connected through the 1:N switches change-over part 114 is output.

In the present embodiment, from which a transmission electric powercontrol signal is output is an arbitrary SIR calculating part to which acalibration signal is input, so that such an advantage that acalibration period can be reduced in a reception branch in question. Itis to be noted that operations are the same as those of the secondembodiment except that a transmission electric power is controlled inthe present embodiment.

Fourth Embodiment

FIG. 9 is a block diagram illustrating an array antenna receiver of thefourth embodiment according to the present invention which is differentfrom the first embodiment of FIG. 2 in that BER calculating parts 115 ₁to 115 _(N) are used in place of the SIR calculating part 111 ₁ to theSIR calculating part 111 _(N), and a BER threshold value establishingpart 116 is used in place of the SIR threshold value establishing part112, while the other constructions are the same as those of FIG. 2.

In the first embodiment, although a SIR of a calibration signalextracted from each radio receiving part of an antenna is calculated inthe SIR calculating part 111 ₁ to the SIR calculating part 111 _(N), theother manner is also applicable so far as the manner relating to amethod for measuring signal quality. In the present embodiment, a biterror rate is calculated with respect to a calibration signal by meansof the BER calculating parts 115 ₁ to 115 _(N), while the BER thresholdvalue establishing part 116 outputs a BER threshold value. As describedabove, the same advantageous effects as those of the former embodimentscan be achieved, even if BER is used in place of SIR.

Furthermore, the fourth embodiment may be modified, as a matter ofcourse, as in the second embodiment in such that multiplex circuits arechanged over in accordance with a time sharing manner by the use of the1: N switches change-over part 114, or as in the third embodiment insuch that a transmission electric power of a calibration signal iscontrolled by the use of the power level variable part 108.

In the above-described embodiments, although an example of a receiverdevice using an array antenna wherein antenna elements are disposed soas to attain high correlations among the antenna elements is described,the present invention is not limited thereto, but it is also applicableto a receiver device using an antenna wherein antenna elements aredisposed so as to attain low correlations among the antenna elements.

INDUSTRIAL APPLICABILITY

As described above, the present invention has the following advantageouseffects. Namely, a first advantage can realize a calibration method bywhich the best efficient calibration period is held in each receptionbranch, and maintained at constant calibration accuracy. The reason ofwhich is in that a calibration is independently carried out in eachbranch, and a period of a calibration continues until a SIR value of acalibration signal calculated in each reception branch exceeds anestablished SIR threshold value.

A second advantageous effect is to be capable of providing a calibrationmethod by which a reception branch wherein a trouble appears isexcluded. The reason of which is in that when quality of a calibrationsignal (a required SIR or BER) is not assured in each reception branch,reception signal information from the reception branch in question ismade to be ineffective.

A third advantageous effect is to be capable of providing a calibrationmethod by which reception sensitivity of a user signal (desired wave)deteriorates scarcely due to a cause of a calibration signal in respectof a mobile phone. The reason of which is in that a calibration signalof a fixed level being sufficiently smaller than a noise electric poweris input to each radio reception part of an antenna, so that a noiseelectric power level is scarcely elevated. Besides, since a calibrationsignal of an electric power suitable for one reception branch is outputeven in a case where a transmission electric power of a calibrationsignal is controlled, there is no influence with respect to receptionsensitivity of a user signal.

A fourth advantageous effect is to be capable of providing a calibrationmethod by which the number of users in a cellular system is scarcelyreduced. The reason of which is in that a calibration signal of a fixedlevel being sufficiently smaller than a noise electric power is input toeach radio reception part of an antenna, and an averaging process iscontinued until a SIR required for conducting a calibration in eachreception branch, so that there is not such a case where a calibrationsignal changes into an interference signal to make a ratio of a usersignal from a mobile phone to the interference signal inferior, wherebya transmission output of the mobile phone is allowed to increase fordemodulating the user signal in question up to signal quality desired ina base station installation.

1. An array antenna receiver device comprising: a plurality of antennaelements; a means for outputting calibration signals; a means fordistributing the calibration signals to the plurality of the antennaelements; a plurality of multiplexing means each of which multiplexeseach calibration signal distributed with a signal input from each of theplurality of the antenna elements; a plurality of SIR calculating meanseach of which extracts and demodulates each calibration signal from anoutput signal of the multiplexing means to calculate a SIR (Signal toInterference Ratio) value, and further compares the SIR value calculatedwith a previously established SIR threshold value thereby to outputreception branch information and a demodulation result of thecalibration signal only when the SIR value calculated exceeds the SIRthreshold value; a means for storing a reference demodulation resultwhich is previously established in each reception branch; a means fordetecting a calibration amount of amplitude/phase information in eachreception branch based on the demodulation result and the referencedemodulation result in a branch corresponding to the storing means; andmeans for correcting a user signal based on the calibration amount. 2.The array antenna receiver device as defined in claim 1 wherein anelectric power of the calibration signal is a fixed electric powersufficiently smaller than a noise electric power in a receiver of aradio base station installation.
 3. The array antenna receiver device asdefined in claim 1 wherein a calibration period for updating acalibration amount in each reception branch differs from one another inevery reception branch or in each period of time in the same receptionbranch.
 4. The array antenna receiver device as defined in claim 1wherein the calibration amount calculating means calculates acalibration amount with respect to only a reception branch to which ademodulation result of a calibration signal is input.
 5. The arrayantenna receiver device as defined in claim 1 wherein when the SIR valuedoes not reach a SIR threshold value, a user signal in a receptionbranch in question is made to be ineffective as a result of judging thata problem appears in the reception branch in question.
 6. The arrayantenna receiver device as defined in claim 1 wherein a BER (Bit ErrorRate) is used in place of the SIR value.
 7. The array antenna receiverdevice as defined in claim 1, wherein a problem detection signal isoutput when the SIR value calculated does not exceed the SIR thresholdvalue.
 8. The array antenna receiver device as defined in claim 1,wherein each of the plurality of calculating means calculates the SIRvalue for a period of calibration until the SIR value calculated exceedsthe SIR threshold value.
 9. An array antenna receiver device comprisinga plurality of antenna elements; a means for outputting calibrationsignals; a plurality of multiplexing means for multiplexing each outputsignal from the plurality of the antenna elements with each calibrationsignal; a means for changing over connections of the output means withthe plurality of the multiplexing means to supply calibration signals ina time sharing manner to the plurality of the multiplexing means; aplurality of SIR calculating means for extracting and demodulatingsuccessively calibration signals from output signals of one multiplexingmeans selected respectively in synchronous with supplying operations ofthe calibration signals from the supplying means in accordance with thetime sharing maimer to calculate a SIR (Signal to Interference Ratio)value, and further compares the SIR value calculated with a previouslyestablished SIR threshold value thereby to output reception branchinformation and a demodulation result of each calibration signal in onlythe case when the SIR value calculated exceeds the SIR threshold value;a means for storing a reference demodulation result which is previouslyestablished in each reception branch; a means for detecting acalibration amount of amplitude/phase information in each receptionbranch based on the demodulation result arid the reference demodulationresult in a branch corresponding to the storing means; and means forcorrecting a user signal based on the calibration amount.
 10. The arrayantenna receiver device as defined in claim 9 comprising further a meansfor controlling a transmission electric power of a calibration signalbased on a control signal in response to a SIR value of the SIRcalculating means.
 11. The array antenna receiver device as defined inclaim 9 wherein the supplying means changes over connections with themultiplexing means based on reception branch information from the SIRcalculating means.
 12. The array antenna receiver device as defined inclaim 9 wherein an electric power of the calibration signal is a fixedelectric power sufficiently smaller than a noise electric power in areceiver of a radio base station installation.
 13. The array antennareceiver device as defined in claim 9 wherein when the SIR value doesnot reach a SIR threshold value, a user signal in a reception branch inquestion is made to be ineffective as a result of judging that a problemappears in the reception branch in question.
 14. The array antennareceiver device as defined in claim 9 wherein a BER (Bit Error Rate) isused in place of the SIR value.
 15. A calibration method of antennareception signals comprising the steps of: multiplexing a receptionsignal input in every plural antenna elements with a calibration signaldistributed in the every plural antenna elements; extracting anddemodulating a calibration signal from the multiplexed signal tocalculate a SIR (Signal to Interference Ratio) value of the calibrationsignal; comparing the SIR value calculated with a previously establishedSIR threshold value to output reception branch information and ademodulation result of the calibration signal only when the calculatedSIR value exceeds the SIR threshold value; detecting a calibrationamount of amplitude/phase information in every reception branch based onthe demodulation result and the previously established referencedemodulation result; and correcting a user signal based on thecalibration amount.
 16. A calibration method of antenna receptionsignals comprising the steps of: multiplexing a reception signal inputin every plural antenna elements with each calibration signal suppliedin a time sharing manner in the every plural antenna elements;extracting and demodulating successively calibration signals from onemultiplexing signal selected respectively in synchronous with supplyingoperations of the calibration signals in accordance with the timesharing manner to calculate a SIR (Signal to Interference Ratio) valueof each calibration signal; comparing the SIR value calculated with apreviously established SIR threshold value to output reception branchinformation and a demodulation result of the calibration signal onlywhen the calculated SIR value exceeds the SIR threshold value; detectinga calibration amount of amplitude/phase information in every receptionbranch based on the demodulation result and the previously establishedreference demodulation result; and correcting a user signal based on thecalibration amount.